1. Field of the Invention
This invention relates to an optical pickup device for illuminating a light beam radiated from a light source on an optical disc loaded and rotationally driven on a disc rotating driving unit, for reading out the information signals recorded on the optical disc and/or recording information signals on the optical disc.
2. Background of the Invention
Up to now, an optical pickup device has been in use for converging a light beam radiated from a light source, such as a semiconductor laser, by an objective lens, and for illuminating the converged light beam, in order to read out the information signals recorded on the optical disc, or in order to record the information signals on the optical disc.
This sort of the optical pickup device is provided with optical components, such as a reflective mirror for guiding the light beam radiated from the light source to an objective lens or a photodetector for detecting the light beam reflected back from the optical disc.
Meanwhile, if, in an optical disc, dust and dirt have become affixed to the optical components, such as an objective lens or a reflective mirror, the volume of the light transmitted through the respective components is decreased to diminish the light volume to decrease the volume of the light incident on the photodetector to render it impossible to read out the information signals recorded on the optical disc accurately.
Thus, in a conventional optical pickup device, the objective lens arranged on an optical block and an objective lens driving unit adapted to move the objective lens along the optical axis of the objective lens and along a direction perpendicular to the optical axis of the objective lens, based on the focussing error signals and the tracking error signals, are covered by a lid, in order to prevent dust and dirt from becoming attached to the objective lens and in order to prevent duct and dirt from invading into the inside of the optical block, in which are housed the optical components, such as a reflective mirror or a photodetector.
The lid covering the objective lens and the objective lens driving unit is provided with a through-hole to permit the light beam transmitted through the objective lens so as to be illuminated on the optical disc and the light beam reflected back from the optical disc to fall on the objective lens. This through-hole is sized to be large enough to permit driving displacement of the objective lens therein. As a result, dust and dirt are intruded through this through-hole into the inside of the lid to contaminate the objective lens or other optical components in the optical block.
In order to prevent intrusion of dust and dirt through the through-hole provided in the lid covering e.g., the objective lens, an optical pickup device has been proposed in which a shutter for opening or closing the through-hole is provided in the lid. If, in such case, the shutter is not reliably opened or closed, there is a risk that the light beam from the light source be not illuminated on the optical disc. On the other hand, if a driving source provided on the disc recording and/or reproducing apparatus provided with the optical pickup device is utilized, the result is a complicated mechanism of the device.
In the Japanese Laying-Open Patent H-06-005062, there is disclosed a disc reproducing apparatus in which, if disc rotation is halted, the optical pickup is moved to a portion below the roof provided on the outer rim side of a disc housing recess to protect the optical pickup. Since the optical pickup proposed in the Japanese Laying-Open Patent H-06-005062 is moved to a portion below the roof in such a state in which the pickup is spaced apart from the roof, there is maintained a clearance which is large enough to prevent the roof from obstructing the movement of the optical pickup. Thus, only the movement means for causing the movement of the optical pickup serves as means for holding the optical pickup moved to the lower side of the roof, such that there is a possibility of the optical pickup being moved under an impact from outside.
It is therefore an object of the present invention to provide an optical pickup device and optical disc recording and/or reproducing apparatus which is free from the above-mentioned drawbacks.
The present invention provides an optical pickup device for recording and/or reproducing information signals for an optical disc by an optical pickup, the optical pickup device including an optical pickup unit, which optical pickup unit has an objective lens for converging a light beam radiated from a light source and for illuminating the converged light beam on the optical disc run in rotation by a disc rotating driving unit, an objective lens driving unit for driving and displacing the objective lens at least in a direction along the optical axis of the objective lens and a lid for covering the objective lens and the objective lens driving unit, having a through-hole for transmitting the light beam converged by the objective lens towards the optical disc. The optical pickup device also includes an optical pickup feed unit for feeding the optical pickup unit along the radial direction of the optical disc and for causing movement of the optical pickup unit until the objective lens is located on an outer rim side of the optical disc loaded on the disc rotating driving unit, a cover plate for covering the through-hole of the lid when the optical pickup unit is moved by the optical pickup feed unit until the objective lens is located outwardly of the optical disc loaded on the disc rotating driving unit, an abutting portion provided on one of the lid and the cover plate, and which is adapted for causing movement of the cover plate in a direction away from the objective lens when the optical pickup unit is moved by the optical pickup feed unit so that the objective lens is positioned outwardly of the optical disc. The optical pickup device also includes an engagement portion provided on the other of the lid and the cover plate, the engagement portion engaging with the abutting portion when, after the cover plate is moved by the abutting portion in a direction away from the objective lens, the optical pickup unit is further moved to outwardly of the optical disc by the optical pickup unit.
In the optical pickup device according to the present invention, the through-hole provided in the lid, which covers the objective lens and the objective lens driving unit can be covered by a cover plate during storage when the information signals are not recorded not reproduced on or from an optical disc, or during the time the optical pickup device is otherwise not used for prolonged time. Thus, it is possible to prevent dust and dirt from invading into the inside of the optical pickup unit to become affixed to optical components provided in the optical block to decrease the light volume of the light beam illuminated on the optical disc or reflected back from the optical disc to assure stable recording and/or reproduction of information signals.
In addition, with the optical pickup device according to the present invention, the cover plate and the lid are engaged with each other when the through-hole provided in the lid which covers the objective lens and the objective lens driving unit is covered by the cover plate, thus enabling the optical pickup to be held in stability against an external shock.
Moreover, with the optical pickup device according to the present invention, the opening in the cover plate and the abutting portion on the lid are engaged with each other when the through-hole provided in the lid which covers the objective lens and the objective lens driving unit is covered by the cover plate to provide a clearance narrower than the clearance between the roof of the Japanese Laying-Open Patent H-06-005062 and the optical pickup, thus more effectively preventing dust and dirt from invading into the inside of the optical pickup unit.